Reciprocating piston pump

ABSTRACT

A reciprocating high-pressure pump assembly is provided, having a housing, a piston reciprocably mounted in a cylindrical chamber of the housing, and an outlet port and valve assembly mounted at the upper part of the housing. A pair of inlet port and valve assemblies are additionally mounted in the housing, one substantially coaxially with the piston, and the other substantially coaxially with the outlet valve, and in a lower portion of the housing. This structure, because it utilizes two inlet valve assemblies, permits inlet valves and housings to be utilized of considerably reduced dimensions, thereby greatly increasing the trouble-free operating time of the pump without reducing pumping capacity, and additionally permitting a plurality of pump assemblies to be mounted side by side in closer relationship than is possible with prior art pumps.

United States Patent [151 3,679,332

Yohpe 5] July 25, 1972 54] RECIPROCATING PISTON PUMP 3,146,724 9/1964 Cornelsen ..417/539 [72] lnventor: Reinhard A. Yohpe, Battle Creek, Mich. Primary Examiner wmiam L- Freeh [73] Assignee: Union Pump Company, Battle Creek, Attorney-Roy A. Plant Mich. 22 Filed: April 10, 1970 [57] ABSTRACT [21] Appl 27,330 A reciprocating high-pressure pump assembly is provided,

having a housing, a piston reclprocably mounted in a Cylllldflcal chamber of the housing, and an outlet port and valve as- [52] U.S. Cl ..4l7/503, 417/570 bly mounted at the upper part of the housing. A pair of l inlet port and valve assemblies are additionally mounted in the [58] Field of Search ..4l7/454, 503, 569, 570, 568 housing one substantially coaxiany with the piston, and the other substantially coaxially with the outlet valve, and in a [56] References Cned lower portion of the housing. This structure, because it utilizes two inlet valve assemblies, permits inlet valves and housings to UNITED STATES PATENTS be utilized of considerably reduced dimensions, thereby 3,373,695 3/ 1968 Yophe ..41 7/5 69 greatly increasing the trouble-free operating time of the pump 1,297,035 3/1919 Stratton ..4l7/503 without reducing pumping capacity, and additionally per- 2,364,550 12/1944 F mitting a plurality of pump assemblies to be mounted side by 1,322,236 1 H1919 Fish side in closer relationship than is possible with prior art 2,266,125 12/1941 Malsbary et al. .....4l7/503 pumps 3,427,988 2/1969 Redmann et al.... .....4l7/569 2,168,850 8/1939 Towler et al ..417/569 9 Claims, 3 Drawing Figures Ii 3 /da 12 I m 7/ f /i-i 54 5,376 16 W I! 79 .J 73 7 40 46 5 43 if 37 ll, l7 "LC 2; v

4/ 4 z; 63 g; t i: M w

,\/\v I if ZZ-kl' I .55 f l I 35 j! M I 1 55 '24 m4 u \f 7 {a PATENTEDJULZS I972 3 679 332 .sum 1 or 2 INVENTOR Z Z REINHARD A. YOHPE TM. 2 BY (Ra ATTORNEY PATENTED JUL 2 5 I972 SHEET 2 UF 2 INVENTOR 'REINHARD A. YOHPE BY GL a (PM ATIORNEY RECIPROCATING PISTON PUMP BACKGROUND OF THE INVENTION This invention relates broadly to liquid pumps, and more specifically to novel valve positioning and construction for high-pressure reciprocating piston pumps.

The rapid advance of modern technology has made increasingly greater demands upon related industrial and commercial fields. Particularly, the pump industry has been called upon to furnish pumping equipment for various new applications and even old applications with more stringent specification demands in many fields. In some cases existing equipment or equipment utilizing standard principles can be readily adapted to these applications. The pumping industry has made important contributions to the oil industry, for example, in operations known as secondary recovery. It has proved beneficial to inject salt water into oil wells permitting what is called secondary recovery operations which increases the oil productivity in the older well fields. The output pressures required in this operation are generally in the range of 2,000 to 6,000 psi.

Salt water is the liquid usually used in secondary recovery operation." Because it is very corrosive, it causes pump damage generally referred to as stress-corrosive fatigue. This presents itself as cracks generally forming at intersections of bores or chambers. Stress-corrosive fatigue has been shown to occur frequently and cause greater damage as the bore or chamber size increases. Reciprocating pumps have been used in this area as a general practice with the single inlet port and the outlet port being positioned substantially perpendicular to the cylinder wall and generally aligned 180 from each other. When the pumps are operated with shock conditions present, the breakdown possibilities substantially increase. Shock conditions are caused normally by starvation of liquid to the system and by air inclusion in the liquid.

Another important use for high-pressure pumps of the type to which the present invention is devoted is for the pumping of ordinary water to place it under high pressure for such applications as hydraulic cleaning.

Another important use for high-pressure pumps is in the homogenizer field where the materials to be homogenized such as whole milk, ingredients of salad dressings, et cetera, are mixed where necessary for uniformity and forced under high pressure through a homogenizer valve.

The pump structure presently used in the industry for highpressure reciprocating liquid pumps does permit a relatively substantial volumetric clearance of the piston. Because the inlet and outlet ports are across from each other, the bore of the inlet port is required to be larger than desirable so that assembly and manufacturing procedures can be readily accomplished. Because of this and other reasons, the piston cylinder bore is also required to be fairly large. All these factors contribute to high cost and substantial maintenance expense.

In US. Pat. No. 3,373,695, an improved pump is disclosed and claimed in which the input valve is positioned substantially coaxially with the piston. This structure has resulted in improved operation. However, because the input valve and its chamber assembly must necessarily be rather large in order to handle the entire input demand, there are limited fields of application, as for example for the pumping of liquids under exceptionally high pressures, where an improvement in operation, particularly at high speeds, might be desirable. Additionally, because of the size of the input valve assembly, when a plurality of pumps are mounted together in sequential arrangement, they cannot be mounted as close together as desired.

SUMMARY OF THE INVENTION It is a further object to provide a pump of the type described having a structure which permits small distances between centers of pistons and cylinder bores associated with each piston, thereby permitting a plurality of pumps to be arranged in close side-by-side proximity.

It is a further object to provide a pump which is relatively small and economical to manufacture and to operate, while still having high capacity.

It is an additional object to provide a pump which may be operated at very high speeds without subjecting the pump structure to excessive shock loadings.

It is a still furtherobject to provide a pump which may be easily maintained and serviced.

Still further objects and advantages of the invention will appear as the description proceeds.

To the accomplishment of the foregoing and related ends, the invention, then, consists of a high-pressure reciprocable pump having a single outlet valve and a pair of inlet valves, one mounted substantially coaxially with respect to the operating piston, and the other mounted substantially perpendicularly to the piston and substantially coaxially with the outlet valve. The resulting structure utilizing two inlet valves permits the valves and their accompanying structures to be made considerably smaller individually, thereby reducing the surface area subject to corrosion and shock stress, and permitting a plurality of pumps to be mounted side-by-side close together for operation by a single power source.

BRIEF DESCRIPTION OF THE DRAWINGS In the annexed drawings:

FIG. 1 is a side elevational view illustrating'a pump member having a structure provided with the improvement of the present invention.

FIG. 2 is a front elevational view, partially broken away, of the pump unit illustrated in and seen from the right-hand side of FIG. 1; and

FIG. 3 is an enlarged partial sectional view taken at the line IIlIIl of FIG. 2, looking in the direction of the arrows.

DESCRIPTION OF THE PREFERRED EMBODIMENT Referring to FIG. 1, numeral 10 refers generally to a pump assembly. The pump assembly 10 has a motor assembly body 11 with a base 12, a frame member 13 and an end cover 14. A cylinder assembly 15 is connected to the frame member 13 and is part of the pump assembly 10.

Referring generally to FIGS. 1 and 2, the cylinder assembly 15 is shown with an inlet pipe 17 connected to an inlet opening 18 of manifold 19. A portion of the liquid to be moved through the pump assembly 10 by cylinder assembly 15 enters from inlet pipe 17 through inlet opening 18 and is distributed to the various cylinder chambers by manifold 19, as will be explained in detail below. A second inlet assembly is mounted at the bottom of the cylinder assembly 15 and comprises an inlet pipe 24, an inlet opening 25, and a manifold 26, FIG. 3. The liquid influent from both inlets passes from the cylinder chamber, through an outlet valve, to a discharge manifold 30. The discharge manifold has a cap assembly 31 on one end, and discharges the liquid through pump assembly outlet membe 32 at its opposite end.

Referring to FIG. 3, the fluid is supplied to the cylinder as sembly 15 through both manifold 19 and manifold 26. The manifold 19 is connected to a cap member 35 by capscrews 36. The manifold is provided with a drainage plug 37. The cap member 35 is connected to a cylinder block 38 by means of bolts 33. The cylinder block 38 comprises a housing defining four interconnecting chambers, an outlet valve chamber 70, a pair of inlet valve chambers 71 and 72, and a cylinder chamber 76. The inlet valve chamber 71 is substantially coaxially arranged with respect to the cylinder chamber 76, and the inlet valve chamber 72 is substantially coaxially arranged with respect to the outlet valve chamber 70, the inlet valve chamber 72 and outlet valve chamber 70 being substantially perpendicular to the inlet valve chamber 71 and cylinder chamber 76.

A common central'chamber 69 formed in the housing of the cylinder block 38 is connected to the outlet valve chamber by an outlet port 75, to the inlet valve chamber 71 by an inlet port 73, to the inlet valve chamber 72 by an inlet port 74, and to the cylinder chamber 76 by a cylinder chamber port 89. In the preferred embodiment, the diameters of the cylinder chamber port 89,-the inletports 73 and 74, and the outlet port 75 are substantially the same, thereby insuring uniform stress forces at the ports, and additionally permitting the piston 93 to be removed through the inlet port 73 when the inlet valve is disassembled, as, for example, when the various pump parts must be cleaned or sterilized frequently after operation.

The inlet valve chamber 71 has an inlet valve assembly ineluding a valve seat member 39 positioned below the cap member 35. A seal 40 is provided between the fold l9 and the cap member 35, and a seal 41 is provided between the valve seat member 39 and the cap member 35. A seal 42 is provided between the valve seat member 39 and the cylinder block 38.

These sealsare utilized to contain' fluid in the cylinder assembly .15, and are part of a well-developed art. A- valve member 43 is mounted in aguide and locating member 45.

The guide ,45 is mounted on the valve seat member 39, and guides the valve member 43 as it moves from open to closed position. The valve member 43 has a threaded end 44 which is engagedby a nut 46 holding a stop member 47 in contact with a compression spring 48. n

The lower inlet valve is similarly constructed in valve chamber 72 and comprises the manifold 26 afiixed to a cap member 55 by means of capscrews 56. A drain plug 57 is provided in the manifold 26. The cap member 55is connected to the cylinder block 38 by means of bolts 58. A valve seat member 59 is positioned between the cap member 55 and cylinder block 38. A'seal 60 is provided between the manifold 26 and the cap member 55, a seal 61 is provided between the valve seat 59 and the cap-member 55, and a seal 62 is provided between the valve seat 59 and cylinderblock 38. A valve,

. valve member 63. Discharge manifold (FIG. 2) is defined bya wall member 77 forming a part of the block 38 and a cover member 78. The cover member 78 is connected to the wall member 77 by studs 79 and nuts 80 and sealed to the block 38 by a seal 50. A valve member 83 is movably positioned with its stem 84 in the channel of a valve guide 85 of the valve seat insert 81. A compression spring 86 acts on a stop member 87 maintaining the valve member in normallyv sealed position. The valve member 83 is provided with a stop member 88 which acts with the-stop member 87 to limit the full open position of the valve member 83.

A portion of the cylinder block 38 defines the cylinder chamber 76. A piston 92 having a plunger end 93 and screw cap 94 is mounted in the chamber 76 and is adapted to slide therein with reciprocating motion. The outer end of the piston 92 is adapted to be connected to a power actuating means. The cylinder chamber 76 is contoured at its outer end to provide a stuffing box 95 having a packing ring 96, a lantern ring or gland 97, and a gland follower ring 98, which make sealing contact between the cylinder assembly and the piston 92. The stuffing box rings 96, 97 and 98 are held in place by an externslly threaded gland nut 99, and locking ring 100. A lubrica- ,tion supply groove 101 fed by a supply tube 102 and provided with a threaded opening 103 provides means for supplying a lubricating sealing medium to the stumng box gaskets. A pressurized lubricating fitting 104 and channel 105 provide lubrication to an annular chamber 106.

When power is suitably applied to the piston 92, it causes the piston to move back and forth in a reciprocating movement with respect to cylinder block 38. As the piston 92 is being drawn away from the valve members, the pressure of the fluid in manifold 19 and manifold 26 causes the valve members 43 and 63 to be withdrawn from their sealed position, permitting the liquid from both inlets to move into the cylinder chamber 76. During this time the compression spring 86 maintains the valve member 83 in its sealed position. After the piston 92 has reached its maximum retracted position, it begins to move back toward the valve members' 43 and 63, causing the valve members43 and 63 to move to their sealed positions with thevalve seats 39 and 59, respectively. At this time the pressure of the liquid in the cylinderchamber 76' causes the valve member 83 to open, thereby permitting fluid to pass into the discharge manifold 30. Succeeding reciprocat:

the inletvalve chamber with which it is substantially coaxial. Moreover, in this embodiment the part of the other inlet valve chamber should be substantially thesame as the diameter of the port of the outlet chamber. In fact, it isadvantageous to make the cylinder chamber bore and the inlet and outlet valve ports of substantially the same diameter. Such structure was impossible in prior art pumps utilizing a single inletvalve and outlet port without adversely'afiecting the pumping capacity and efficiency. The use of smaller ports and smaller inlet valve chamber bores in the present invention reduces hydraulic loading in the cylinder block and on the inlet valve ports, and permits a smaller diameter and lighter bolting for the flanges 35 and which clamp the inlet valve ports .to the cylinder block.

The smaller inlet valve and inlet valve chamber bore is made possible by the addition of a secondset of inlet valve ports located at the bottom of the cylinder block and clamped to the cylinder block in the same manner as those at the front of the block. In the preferred cmbodimentthe second inlet valve chamber bore is positioned at right angles with respect to the piston, and with the inlet valve ports at the front of the cylinder and-communicating with the cylinder bore at right angles thereto. The required inlet liquid flow to the piston chamber is thus obtained through two inlet valves and inlet valve chamberswhich are much smaller than would be neces- In the present invention, only one discharge valve per piston is employed. The discharge valve and valve chamber are also of small diameter in relation to pump capacity, with the result that the port and valve chamber communicating with the cylinder bore at right angles, and the discharge valve chamber bore may be of relatively small diameter. The use ofa discharge valve having a small diameter may result in relatively high liquid velocity through the valve seat bore with higher. than normal discharge pressure loss, but this is relatively unimportant as the loss relative to discharge pressure'of a high-pressure pump is extremely small. The use of such a small bore intersecting the cylinder bore serves to reduce the stresses at the intersecting points of the bores, thus reducing danger of failure at these critical points.

As an illustration of the degree in reduction of inlet valve chamber diameter which has been made possible by the present use of dual inlet valves, one inlet valve coaxial with the cylinder, pumps have been built and placed in service having invention have been in experimental service for more than twenty times the average life of pumps of conventional construction with still no indication of failure.

In the utilization of high pressure pumps, it is common to place a plurality of pumps side by side and operate the group of pumps by a single power source such as an electric motor. When such a structure is utilized it is important that the pumps be placed as closely together as possible, so that the overall units may be small. The present structure facilitates such close spacing for several reasons. Where a single cylinder block is utilized with a plurality of pistons, the maximum center distance between pistons, if not otherwise restricted, is dependent upon the inlet valve chamber diameter and upon the amount of metal required between adjacent valve chambers for adjacent pistons for the pressures involved. Thus, as the inlet valve chamber diameter is reduced, the center distance may be reduced by both the amount of the inlet valve chamber reduction and the reduced amount of metal required to supply adequate strength for the smaller diameter. In the case of individual cylinder blocks for each piston, the same factors apply except that the amount of metal between the inlet valve chamber and the sides of the cylinder block must be considered.

A second consideration is that the minimum center distance between pistons may be limited by the diameter of the closing means employed, as for example by the diameter of the flange 35 as shown in FIG. 3. This diameter depends upon the diameters of the bores in which the inlet valve parts are positioned, the hydraulic loading on the parts, and the size of the bolts required, all of which are smaller for the present structure utilizing two inlet valve structures. The reduced distance between piston centers also permits a smaller and lower cost cylinder block. Additionally, the smaller bores require less machining time. Such economies attain material significance when large pumps are used and more costly cylinder block material required. The smaller center distance between pistons permits a smaller and more economical power unit for driving the pump, and permits the power units to be used which would normally be insufficient for conventional pumps.

The present structure additionally permits higher pump operating speeds to be utilized, especially in larger pump sizes, because the smaller and lighter weight inlet valves have less inertia than large ones utilized with single inlet valve constructions, and therefore less shock is produced with increased speed. Such chock normally increases critical stresses and as a result contributes to cylinder failure. An additional feature of the present structure is that maintenance is relatively simple. The pistons may be readily removed through the cylinder block after the inlet parts are removed which are coaxially arranged with the cylinder chamber. Since these valve parts are smaller and lighter in weight, removal and installation are easier, particularly for large-size pumps.

While but one form of the invention has been shown and described, other forms within the spirit and scope of the invention will now be apparent to those skilled in the art. Therefore the embodiments shown in the drawings are to be considered as merely setting forth the invention for illustrative purposes, and is not intended to limit the scope of the invention herein described, shown and claimed. It is further to be noted that while directional terms have been used, same are not to be construed as a limitation of the invention since such use has been availed of to better describe the invention as used and illustrated in the drawings.

Other modes of applying the principle of my invention may be employed instead of those explained, change being made as regards the means herein disclosed, provided those stated by any of the following claims or their equivalent be employed.

I therefore particularly point out and distinctly claim as my invention:

1. A reciprocating piston pump comprisinG in combination:

a. a housing defining a plurality of interconnecting chambers including, 1. a cylinder chamber, 2.an outlet valve chamber, and

3. a pair of inlet valve chambers;

, b. a piston arranged in said cylinder chamber for reciprocal movement therein and having its outer end adapted to be operatively connected to a power source;

c. an outlet valve assembly mounted in said outlet valve chamber;

d. an inlet valve assembly mounted in each of said inlet valve chambers both inlet valve assemblies opening and closing at substantially the same time and cooperating with said outlet valve assembly;

e. inlet means connected to each of said inlet valve chambers adapted to supply liquid thereto;

f. outlet means connected to said outlet valve chamber adapted to receive liquid therefrom; and

g. a common central chamber within said housing, a cylinder chamber port connecting said cylinder chamber to said common chamber, an outlet valve chamber port connecting said outlet valve chamber to said common chamber, and a pair of inlet valve chamber ports connecting said inlet valve chambers with said common chamber, the diameters of said cylinder chamber port, said outlet valve chamber port, and said inlet valve chamber ports 7 being substantially the same and one of said inlet valve chambers being substantially coaxially arranged with respect to said cylinder chamber.

A reciprocating piston pump comprising in combination:

. a housing defining a plurality of interconnecting chambers including,

1. a cylinder chamber,

2. an outlet valve chamber, and

3. a pair of inlet valve chambers;

. a piston arranged in said cylinder chamber for reciprocal movement therein and having its outer end adapted to be operatively connected to a power source;

c. an outlet valve assembly mounted in said outlet valve chamber and comprising,

1. a valve seat,

2. a valve guide,

3. a valve member movably mounted in said guide, and

4.means biasing said valve member in closed engagement with said valve seat;

d. an inlet valve assembly mounted in each of said inlet valve chambers both inlet valve assemblies opening and closing at substantially the same time and cooperating with said outlet valve assembly each comprising,

1. a valve seat,

2.a valve guide,

3. a valve member movably mounted in said guide, and

4. means biasing said valve member in closed engagement with said valve seat;

e. inlet means connected to each of said inlet valve chambersadapted to supply liquid thereto;

f. outlet means connected to said outlet valve chamber adapted to receive liquid therefrom; and

g. a common central chamber within said housing, a cylinder chamber port connecting said cylinder chamber to said common chamber, an outlet valve chamber port connecting said outlet valve chamber to said common chamber, and a pair of inlet valve chamber ports connecting said inlet valve chamber with said common chamber, the diameter of said cylinder chamber port, said outlet valve chamber port, and said inlet valve chamber ports being substantially the same and one of said inlet valve chambers being substantially coaxially arranged with respect to said cylinder chamber.

3. A reciprocating piston pump according to claim 2, wherein the other of said inlet valve chambers is coaxially arranged with respect to said outlet valve chamber, and wherein said latter inlet valve chamber and said outlet valve chamber are substantially perpendicularly arranged with respect to said first inlet valve chamber and said cylinder chamber.

4. A reciprocating piston pump according to claim 2, wherein said cylinder chamber is contoured to define a stufiing box, said stufiing box having a sealing lubricant absor- 'reciprocal'movemcnt therein and having its outer end adapted to be operatively connected to a power source; c. an ,outlet valve assembly mounted in said outlet valve chamber at the end of each cylinder; d. an inlet valve assembly mounted in each of said inlet valve chambers at the end of each cylinder, both inlet valve assemblies opening and closing at substantially the same time and cooperating with said outlet valve assembly; e. the passage through each of said inlet valve assemblies having a maximum cross-sectional area not substantially larger than the cross-sectional area of the passage in said outlet valve assembly whereby each of said pumps has greater resistance to stress-corrosive fatigue and shock, and said plurality of pumps may be mounted Y in a more compact side-by-side relationship. v

f. inlet mans connected to each of said inlet valve chambers adapted to supply liquid thereto; and

g. outlet means adapted to receive liquid from said outlet valve chamber;

h. one of said inlet valve chambers being substantially coaxially arranged with respect to said piston;

II. a motor and means operatively connecting said motor with the end of each of said pistons;

[I]. an inlet manifold means connected to each of said inlet means for supplying liquid thereto; and

IV. an outletmanifold means connected to each of said outlet means and adapted to receive liquid therefrom. 6. A pump assembly comprising: l. a plurality of reciprocating piston pumps mounted side by side, each pump comprising in combination:

a. a housing defining a plurality of interconnecting chambers including,

1. a cylinder chamber, 2. an outlet valve chamber, and 3. a pair of inlet valve chambers;

b. a piston arranged in said cylinder chamber for reciprocal movement therein and having its outer end adapted to be operatively connected to a power source;

c. an outlet valve assembly mounted in said outlet valve chamber,

1. a valve seat, 2. a valve guide,

3. a valve member movably rnounted in said guide, and 4. means biasing said valve. member in closed engagement with'said valve seat;

d. an inlet valve assembly mounted in each of said inlet valve chambers, both inlet valve assemblies opening and closing at substantially the same time and cooperating with said outlet valve assembly, eac'h comprising! l. a valve seat, 2. a valve guide, 3. a valve member movably mounted in said guide, and 4. means biasing said valve member in closed engagement with said valve seat; H e. the passage through each of saidinlet valve assemblies having a maximum cross-sectional area not substan tially larger than thecross-sectional area of the passage in said outlet valve assembly whereby each of said pumps has greater resistance to stress-corrosive fatigue and shock, and said plurality of pumps may be mounted in a more compact side by side relationship, v f. inlet means connected to each of said inlet valve chambers adapted to supply liquid thereto; and

g. outlet means adapted to receive liquid from said outlet valve chamber;

b. in each pump one of said inlet valve chambers being substantially coaxially arranged ,with respect to said piston; I

H. aninlet manifold means connected to each of said inlet means for supplying liquid thereto, and

Ill. an inlet manifold means connected to each of said inlet I ranged with respect to said outlet valve chamber, andwherein said latter inlet valve chamber and said outlet valve chamber I are substantially perpendicularly arranged with respect to said first inlet valve chamber and said cylinder chamber.

8. A pump assembly according to claim 6, having in each pump a central common chamber within said housing, a cylinder chamber port connecting said cylinder chamber to said common chamber, an outlet valve chamber port connecting said outlet valve chamber to said common chamber, and a 

1. A reciprocating piston pump comprisinG in combination: a. a housing defining a plurality of interconnecting chambers including,
 1. a cylinder chamber, 2.an outlet valve chamber, and
 3. a pair of inlet valve chambers; b. a piston arranged in said cylinder chamber for reciprocal movement therein and having its outer end adapted to be operatively connected to a power source; c. an outlet valve assembly mounted in said outlet valve chamber; d. an inlet valve assembly mounted in each of said inlet valve chambers both inlet valve assemblies opening and closing at substantially the same time and cooperating with said outlet valve assembly; e. inlet means connected to each of said inlet valve chambers adapted to supply liquid thereto; f. outlet means connected to said outlet valve chamber adapted to receive liquid therefrom; and g. a common central chamber within said housing, a cylinder chamber port connecting said cylinder chamber to said common chamber, an outlet valve chamber port connecting said outlet valve chamber to said common chamber, and a pair of inlet valve chamber ports connecting said inlet valve chambers with said common chamber, the diameters of said cylinder chamber port, said outlet valve chamber port, and said inlet valve chamber ports being substantially the same and one of said inlet valve chambers being substantially coaxially arranged with respect to said cylinder chamber.
 2. a valve guide,
 2. A reciprocating piston pump comprising in combination: a. a housing defining a plurality of interconnecting chambers including,
 2. an outlet valve chamber, and
 2. an outlet valve chamber, and
 2. an outlet valve chamber, and
 2. a valve guide,
 2. a valve guide,
 3. a valve member movably mounted in said guide, and
 3. a valve member movably mounted in said guide, and 4.means biasing said valve member in closed engagement with said valve seat; d. an inlet valve assembly mounted in each of said inlet valve chambers both inlet valve assemblies opening and closing at substantially the same time and cooperating with said outlet valve assembly each comprising,
 3. a valve member movably mounted in said guide, and
 3. a pair of inlet valve chambers; b. a piston arranged in said cylinder chamber for reciprocal movement therein and having its outer end adapted to be operatively connected to a power source; c. an outlet valve assembly mounted in said outlet valve chamber,
 3. a pair of inlet valve chambers; b. a piston arranged in each said cylinder chamber for reciprocal movement therein and having its outer end adapted to be operatively connected to a power source; c. an outlet valve assembly mounted in said outlet valve chamber at the end of each cylinder; d. an inlet valve assembly mounted in each of said inlet valve chambers at the end of each cylinder, both inlet valve assemblies opening and closing at substantially the same time and cooperating with said outlet valve assembly; e. the passage through each of said inlet valve assemblies having a maximum cross-sectional area not substantially larger than the cross-sectional area of the passage in said outlet valve assembly whereby each of said pumps has greater resistance to stress-corrosive fatigue and shock, and said plurality of pumps may be mounted in a more compact side-by-side relationship. f. inlet mans connected to each of said inlet valve chambers adapted to supply liquid thereto; and g. outlet means adapted to receive liquid from said outlet valve chamber; h. one of said inlet valve chambers being substantially coaxially arranged with respect to said piston; II. a motor and means operatively connecting said motor with the end of eAch of said pistons; III. an inlet manifold means connected to each of said inlet means for supplying liquid thereto; and IV. an outlet manifold means connected to each of said outlet means and adapted to receive liquid therefrom.
 3. A reciprocating piston pump according to claim 2, wherein the other of said inlet valve chambers is coaxially arranged with respect to said outlet valve chamber, and wherein said latter inlet valve chamber and said outlet valve chamber are substantially perpendicularly arranged with respect to said first inlet valve chamber and said cylinder chamber.
 3. a pair of inlet valve chambers; b. a piston arranged in said cylinder chamber for reciprocal movement therein and having its outer end adapted to be operatively connected to a power source; c. an outlet valve assembly mounted in said outlet valve chamber and comprising,
 3. a pair of inlet valve chambers; b. a piston arranged in said cylinder chamber for reciprocal movement therein and having its outer end adapted to be operatively connected to a power source; c. an outlet valve assembly mounted in said outlet valve chamber; d. an inlet valve assembly mounted in each of said inlet valve chambers both inlet valve assemblies opening and closing at substantially the same time and cooperating with said outlet valve assembly; e. inlet means connected to each of said inlet valve chambers adapted to supply liquid thereto; f. outlet means connected to said outlet valve chamber adapted to receive liquid therefrom; and g. a common central chamber within said housing, a cylinder chamber port connecting said cylinder chamber to said common chamber, an outlet valve chamber port connecting said outlet valve chamber to said common chamber, and a pair of inlet valve chamber ports connecting said inlet valve chambers with said common chamber, the diameters of said cylinder chamber port, said outlet valve chamber port, and said inlet valve chamber ports being substantially the same and one of said inlet valve chambers being substantially coaxially arranged with respect to said cylinder chamber.
 3. a valve member movably mounted in said guide, and
 4. means biasing said valve member in closed engagement with said valve seat; e. inlet means connected to each of said inlet valve chambers adapted to supply liquid thereto; f. outlet means connected to said outlet valve chamber adapted to receive liquid therefrom; and g. a common central chamber within said housing, a cylinder chamber port connecting said cylinder chamber to said common chamber, an outlet valve chamber port connecting said outlet valve chamber to said common chamber, and a pair of inlet valve chamber ports connecting said inlet valve chamber with said common chamber, the diameter of said cylinder chamber port, said outlet valve chamber port, and said inlet valve chamber ports being substantially the same and one of said inlet valve chambers being substantially coaxially arranged with respect to said cylinder chamber.
 4. A reciprocating piston pump according to claim 2, wherein said cylinder chamber is contoured to define a stuffing box, said stuffing box having a sealing lubricant absorbent material contained therein, and a radial channel provided in said housing to permit a sealing lubricant to be applied to said absorbent material.
 4. means biasing said valve member in closed engagement with said valve seat; d. an inlet valve assembly mounted in each of said inlet valve chambers, both inlet valve assemblies opening and closing at substantially the same time and cooperating with said outlet valve assembly, each comprising,
 4. means biasing said valve member in closed engagement with said valve seat; e. the passage through each of said inlet valve assemblies having a maximum cross-sectional area not substantially larger than the cross-sectional area of the passage in said outlet valve assembly whereby each of said pumps has greater resistance to stress-corrosive fatigue and shock, and said plurality of pumps may be mounted in a more compact side by side relationship, f. inlet means connected to each of said inlet valve chambers adapted to supply liquid thereto; and g. outlet means adapted to receive liquid from said outlet valve chamber; b. in each pump one of said inlet valve chambers being substantially coaxially arranged with respect to said piston; II. an inlet manifold means connected to each of said inlet means for supplying liquid thereto, and III. an inlet manifold means connected to each of said inlet means for supplying liquid thereto; an IV. an outlet mainfold connected to each of said outlet means and adapted to receive liquid therefrom.
 5. A pump assembly comprising: I. a plurality of reciprocating piston pumps mounted side by side, each pump comprising in combination: a. a housing defining a plurality of interconnecting chambers including,
 6. A pump assembly comprising: I. a plurality of reciprocating piston pumps mounted side by side, each pump comprising in combination: a. a housing defining a plurality of interconnecting chambers including,
 7. A pump assembly according to claim 6 wherein in each pump the other of said inlet valve chambers is coaxially arranged with respect to said outlet valve chamber, and wherein said latter inlet valve chamber and said outlet valve chamber are substantially perpendicularly arranged with respect to said first inlet valve chamber and said cylinder chamber.
 8. A pump assembly according to claim 6, having in each pump a central common chamber within said housing, a cylinder chamber port connecting said cylinder chamber to said common chamber, an outlet valve chamber port connecting said outlet valve chamber to said common chamber, and a pair of inlet valve chamber ports connecting said inlet valve chambers with said common chamber, the diameters of said cylinder chamber port, said outlet valve chamber port, and said inlet valve chamber ports being substantially the same.
 9. A pump assembly according to claim 6, wherein in each pump said cylinder chamber is contoured to define a stuffing box, said stuffing box having a sealing lubricant absorbent material contained therein, and a radial channel provided in said housing to permit a sealing lubricant to be supplied to said absorbent material. 